Pipe joint restraints are widely used for securing one section of pipe to a fitting, such as a tee or elbow, for example. Generally, prior art pipe joint restraint assemblies comprise two ring or gland members which may be multi-segment members and which are secured, respectively, to interconnected sections of pipe or to a section of pipe or spigot and to the pipe fitting. The restraint assemblies are usually interconnected by plural tie-rods or bolts to prevent the joint from separating due to internal fluid pressure differentials or other mechanical forces acting on the piping system. Plastic pipe and pipe fittings have been developed in recent years for a wide variety of piping applications and the development of plastic, particularly polyvinylchloride (PVC), pipe fittings has evolved to meet certain high pressure piping requirements.
The continued development of PVC pipe and pipe fittings, as well as metal pipe and fittings, has required fitting configurations wherein tees, crosses and similar fittings, for example, which have intersecting conduit portions or branches have, particularly for high pressure applications, required reinforcement of the fittings at the intersections of the respective conduit branches. These reinforcements have typically been made in the form of integral molded fillet areas at the intersections of the conduit branches which may be circumferential or comprised spaced apart fillet or gusset-like segments. In any case, the changes in the configuration of such pipe fittings has caused certain problems in applying pipe restraining ring assemblies, to the fittings.
For example, conventional restraining rings, glands or so called backup rings for pipe joint restraint assemblies are typically sized for a particular outside diameter or a limited range of outside diameters of the pipe and pipe fitting bell portion. If larger diameter restraining rings or backup rings are used with the pipe fittings which have the filleted or reinforced conduit branch intersections, these rings are poorly fitted to the pipe joint, are subject to failure or simply do not provide enough interference between the edge of the ring and the pipe or fitting bell collar to provide a suitable restraint. However, the present invention overcomes the problems associated with pipe joint restraints for use with various pipe and pipe fittings having branch conduit intersections which are reinforced by a continuous fillet or by spaced apart fillet segments between the respective branches.